Mechanisms of creation and destruction of polyhalide V centers in irradiated AHC

The mechanisms of creation and destruction of polyhalide V centers in AHC were modeled by the MNDO semiempirical quantum-chemical method. It is shown that X ₃ ⁻ molecules dissociate from the ground state into X ₂ ⁰ and X⁻ and from the triplet state into X ₂ ⁻ and X⁰, whereas X ₅ ⁻ and X ₇ ⁻ molecules dissociate into X ₃ ⁻ and X ₂ ⁰ and X ₅ ⁻ and X ₂ ⁰ , respectively. At room temperatures, X ₃ ⁻ or larger aggregates, which consist only of X ₃ ⁻ centers, form stable polyhalide V centers. It is shown that the thermal stability decreases when going along the series X ₃ ⁻ , X ₅ ⁻ , and X ₇ ⁻ . The radiation-induced instability of stable F centers in AHC at room temperatures is associated with the destruction of X ₃ ⁻ centers and the thermal instability of X ₅ ⁻ and X ₇ ⁻ centers. E. A. Buketov Karaganda State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 50–54, March, 2000.